初一代數(幾何)!!急急急!!!唔該!!!

1) 加直角之2倍於平角的四分之一,是幾度?直角 = 90°
平角 = 180°180/4 + 90x2 = 225°
2) 某角的餘角對其保角之比是5:14,求某角?設某角 = x ,
某角的餘角 = 90 - x ,
其補角 = 180 - x ,(90 - x) : (180 - x) = 5 : 1414(90 - x) = 5(180 - x)1260 - 14x = 900 - 5x360 = 9xx = 40某角 = 40°
3) 某角的一半是保角的四分之一,求某角?設某角 = x ,
其補角 = 180 - x ,x/2 = (180 - x)/42x = 180 - x3x = 180x = 60某角 = 60°
4)某角的保角比其餘角的3倍小30度,求某角?設某角 = x ,
某角的餘角 = 90 - x ,
其補角 = 180 - x ,180 - x = 3(90 - x) - 30180 - x = 270 - 3x - 302x = 60x = 30某角 = 30°